Add an images client.
Add an images client.

This adds support for testing the glance API directly.
We no longer need to use python-glanceclient to run
the images tests.

Fixes bug 1089765
Partially implements blueprint add-glance-api-v1-tests

Change-Id: I404e43e2e6ffecb5131cdcc43df03b8da0e7f0f8

afaheem88/tempest-lib,mtreinish/tempest-lib,sorenh/tempest-lib,varunarya10/tempest-lib,JioCloud/tempest-lib,cneill/tempest-lib